Precisely. It's only 1 percent off. Who says it's all relative anyway? :-)
Whenever cousins marry? ;’)
I think what they mean is that one-percent is the resolution of the experiment, not the accuracy of the theory. In other words, Einstein predicted 0.0018, we measured (say) 0.001801 plus or minus 0.000018 (one sigma), would "confirm" Einstein within 1%. If they measured 0.001901 plus or minus 0.000018, assuming no experimental errors, this would strongly refute Einstein's theory of General Relativity.
There are four classical tests of General Relativity. One is the precession of the perihelion of Mercury. It was the only one that Einstein could check by hand before publishing the theory. He recalled his gratification when his calculation fit the observations. (Anomalies in the orbit of Uranus had lead to the discovery of Neptune and were considered a major victory for Newtonian mechanics. The Newtonians of the early twentieth century were waiting for a break through discovery associated with the precession of the p of M to provide another triumph for Newton. Score one for Einstein.)
Four classical tests of GR:
1.) Precession of the perihelion of Mercury. (Historically confirmed prior to GR.)
2.) Deflection of starlight by Sun during an Eclipse. (Eddington, 1919.)
3.) Red shift of the spectrum of massive stars. (Various)
4.) Delay of trans solar radar echos from inner planets (Shapiro, ~1962.) 2.)